I have a Calstar 90J that has a very long crosswrap on it, and I have applied roughly 5 coats of finish to try and get a nice, level coat but to no avail. It is wavy and nonuniform all the way around. Since I have so many coats of finish would it be possible to run a sanding block over it to level it out, then apply another coat of finish? If it is possible, what would you sand it with? Thanks!